And in some cases, they are our relatives. Thor is not only a bud, but a big brother. We consider Odin and Frigga to be All-Father and All-Mother, respectively, and give the respect due to parents. Other deities could be somewhere between elder siblings and aunts or uncles... that's the kind of respect we pay to them. In fact, the relationship is so close it's very likely that if we were to kneel or bow down to them they'd say "get up!"
First blot I ever did was to Balder. I was mostly improvising, and ended up doing some kneeling gestures.
The Meade spilled all over the floor later that day. LOL